/**
@license
Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
This code may only be used under the BSD style license found at
http://polymer.github.io/LICENSE.txt The complete set of authors may be found at
http://polymer.github.io/AUTHORS.txt The complete set of contributors may be
found at http://polymer.github.io/CONTRIBUTORS.txt Code distributed by Google as
part of the polymer project is also subject to an additional IP rights grant
found at http://polymer.github.io/PATENTS.txt
*/
import '../iron-flex-layout/iron-flex-layout.js';

import {IronMeta} from '../iron-meta/iron-meta.js';
import {Polymer} from '../polymer/polymer_bundled.min.js';
import {dom} from '../polymer/polymer_bundled.min.js';
import {html} from '../polymer/polymer_bundled.min.js';
import {Base} from '../polymer/polymer_bundled.min.js';

/**

The `iron-icon` element displays an icon. By default an icon renders as a 24px
square.

Example using src:

    <iron-icon src="star.png"></iron-icon>

Example setting size to 32px x 32px:

    <iron-icon class="big" src="big_star.png"></iron-icon>

    <style is="custom-style">
      .big {
        --iron-icon-height: 32px;
        --iron-icon-width: 32px;
      }
    </style>

The iron elements include several sets of icons. To use the default set of
icons, import `iron-icons.js` and use the `icon` attribute to specify an icon:

    <script type="module">
      import "../iron-icons/iron-icons.js";
    </script>

    <iron-icon icon="menu"></iron-icon>

To use a different built-in set of icons, import the specific
`iron-icons/<iconset>-icons.js`, and specify the icon as `<iconset>:<icon>`.
For example, to use a communication icon, you would use:

    <script type="module">
      import "../iron-icons/communication-icons.js";
    </script>

    <iron-icon icon="communication:email"></iron-icon>

You can also create custom icon sets of bitmap or SVG icons.

Example of using an icon named `cherry` from a custom iconset with the ID
`fruit`:

    <iron-icon icon="fruit:cherry"></iron-icon>

See `<iron-iconset>` and `<iron-iconset-svg>` for more information about how to
create a custom iconset.

See the `iron-icons` demo to see the icons available in the various iconsets.

### Styling

The following custom properties are available for styling:

Custom property | Description | Default
----------------|-------------|----------
`--iron-icon` | Mixin applied to the icon | {}
`--iron-icon-width` | Width of the icon | `24px`
`--iron-icon-height` | Height of the icon | `24px`
`--iron-icon-fill-color` | Fill color of the svg icon | `currentcolor`
`--iron-icon-stroke-color` | Stroke color of the svg icon | none

@group Iron Elements
@element iron-icon
@demo demo/index.html
@hero hero.svg
@homepage polymer.github.io
*/
Polymer({
  _template: html`
    <style>
      :host {
        @apply --layout-inline;
        @apply --layout-center-center;
        position: relative;

        vertical-align: middle;

        fill: var(--iron-icon-fill-color, currentcolor);
        stroke: var(--iron-icon-stroke-color, none);

        width: var(--iron-icon-width, 24px);
        height: var(--iron-icon-height, 24px);
        @apply --iron-icon;
      }

      :host([hidden]) {
        display: none;
      }
    </style>
`,

  is: 'iron-icon',

  properties: {

    /**
     * The name of the icon to use. The name should be of the form:
     * `iconset_name:icon_name`.
     */
    icon: {type: String},

    /**
     * The name of the theme to used, if one is specified by the
     * iconset.
     */
    theme: {type: String},

    /**
     * If using iron-icon without an iconset, you can set the src to be
     * the URL of an individual icon image file. Note that this will take
     * precedence over a given icon attribute.
     */
    src: {type: String},

    /**
     * @type {!IronMeta}
     */
    _meta: {value: Base.create('iron-meta', {type: 'iconset'})}

  },

  observers: [
    '_updateIcon(_meta, isAttached)',
    '_updateIcon(theme, isAttached)',
    '_srcChanged(src, isAttached)',
    '_iconChanged(icon, isAttached)'
  ],

  _DEFAULT_ICONSET: 'icons',

  _iconChanged: function(icon) {
    var parts = (icon || '').split(':');
    this._iconName = parts.pop();
    this._iconsetName = parts.pop() || this._DEFAULT_ICONSET;
    this._updateIcon();
  },

  _srcChanged: function(src) {
    this._updateIcon();
  },

  _usesIconset: function() {
    return this.icon || !this.src;
  },

  /** @suppress {visibility} */
  _updateIcon: function() {
    if (this._usesIconset()) {
      if (this._img && this._img.parentNode) {
        dom(this.root).removeChild(this._img);
      }
      if (this._iconName === '') {
        if (this._iconset) {
          this._iconset.removeIcon(this);
        }
      } else if (this._iconsetName && this._meta) {
        this._iconset = /** @type {?Polymer.Iconset} */ (
            this._meta.byKey(this._iconsetName));
        if (this._iconset) {
          this._iconset.applyIcon(this, this._iconName, this.theme);
          this.unlisten(window, 'iron-iconset-added', '_updateIcon');
        } else {
          this.listen(window, 'iron-iconset-added', '_updateIcon');
        }
      }
    } else {
      if (this._iconset) {
        this._iconset.removeIcon(this);
      }
      if (!this._img) {
        this._img = document.createElement('img');
        this._img.style.width = '100%';
        this._img.style.height = '100%';
        this._img.draggable = false;
      }
      this._img.src = this.src;
      dom(this.root).appendChild(this._img);
    }
  }
});
